The present invention relates to a new antibiotic, identified as XK-62-2, and a process for producing the same. More particularly, the present invention relates to a process which comprises culturing an antibiotic XK-62-2 producing microorganism belonging to the genus Micromonospora in a suitable medium to form a novel antibiotic XK-62-2, and recovering the antibiotic from the culture liquor.
The new antibiotic XK-62-2 is a water-soluble, basic antibiotic which has very strong antibacterial activity both in vitro and in vivo against various Gram-positive and Gram-negative bacteria. It also possesses strong antibacterial activity against certain strains of Staphylococcus aureus and Escherichia coli which are resistant to various known antibiotics. Moreover, the present antibiotic is very effective upon the microorganisms of the genus Proteus and Pseudomonas upon which very few antibiotics have been known to be effective; and of the microorganisms of the genus Pseudomonas, the present antibiotic is especially effective upon the strains which are resistant to antibiotic gentamicin C.sub.1a. (Cooper et al: Journal of Chemical Society 1971, p. 3126-3129).
It has been found that XK-62-2 exhibits very excellent therapeutic effect upon various infections (of human beings and animals) caused by the above-described various pathogenic bacteria. In view of this excellent antibacterial activity, XK-62-2 may be used for medicinal purposes as an antibiotic. It may also be used as an additive for animal feed as a growth promoter.
Due to its nature, which will be more fully described hereinafter, it is believed that the new antibiotic belongs to the gentamicin complex.
The production of the basic antibiotic, gentamicin is disclosed in U.S. Pat. No. 3,091,572. Thus, it is known that gentamicin as well as two additional fractions, identified as fraction A and fraction B, may be produced by microorganisms belonging to the species, Micromonospora echinospora and Micromonospora purpurea. Additional researchers have determined that the gentamicin complex contains an additional six components. "Separation, Structural and Physical Studies on the Gentamicin C Complex," Kershner, Rutgers, the State University of New Jersey, 1971. These six components are designated as: C.sub.1, C.sub.2a, C.sub.2 -I, C.sub.2 -II, C.sub.2 -III, and C.sub.1a.
The antibiotic of the present invention is most closely related to the fraction C.sub.2a, but due to significant differences in Nuclear Magnetic Resonance spectra, as will also be more fully described hereinafter, the antibiotic of the present invention is considered different from the fraction C.sub.2a, as reported in the known art.